For many people, carpenter bees are considered a nuisance. Due to their penchant for burrowing into wood, they have become known as a pest to frustrated homeowners. But these bees are more than their nesting habits—they are important pollinators. There are over 500 species of carpenter bee globally, and each one is an integral part of its local ecology.
Most bees are feared for their sting. A huge, yellow and black body accompanied by a loud buzz can send even the bravest of humans running for safety. In the case of carpenter bees, this fear is mostly unwarranted. Male carpenter bees are territorial and protective of their nests, darting after anything that gets too close and sometimes even hovering a short distance away from perceived threats. But despite their seemingly aggressive behavior, carpenter bees are a gentle species. While the females will sting if deliberately provoked (e.g. handled), male carpenter bees, much like honey bee drones, lack stingers. Humans might interpret their behavior as hostile, but these bees are just protecting their home.
Though the species are similar to each other, there are a few key differences between bumblebees and carpenter bees. Bumble bees are a large species with yellow and black markings on their plump, hair-covered bodies. They build their nests underground and divide their time between their nests and foraging for food. Bumble bees are social creatures, forming colonies of up to 50 individuals with a single queen.
Carpenter bees resemble bumble bees in both size and coloring, but the upper surface of their abdomen has little hair and can range from shiny black to green to blue. Depending on the species, male carpenter bees may have large eyes to patrol for potential mates, or small heads with large pheromone reserves to attract females. This species is solitary; while several young bees will emerge from the same nest, they will go their separate ways as adults, only sharing a nest when they have mated.
Due to their short mouthparts, carpenter bees are important pollinators for open-faced or shallow flowers; for some, such as passion flowers, carpenter bees are the sole pollinating species. As they visit flowers and feed on nectar, they pick up and transfer pollen to other flowers.
They are important pollinators for native plant communities, gardens, and even some crops—of $29 billion in value attributed to insect pollination, 15% of that value comes from native species like the carpenter bee. These bees are also important for pollinating wild plants, contributing a food source for birds and other wildlife. Having a stable carpenter bee population encourages a stable ecosystem!
Carpenter bees are named for their incredible nesting method: drilling tunnels into old wood. A common misconception, these bees don’t actually eat wood—they excavate it with their razor-sharp mandibles, leaving tell-tale deposits of sawdust beneath the entrance of their nest. They prefer bare, unpainted, or weathered softwoods, and are especially fond of redwood, cedar, cypress, and pine.
The female carpenter bee will bore a perfectly round hole into the wood (about ½ an inch in diameter), usually against the grain of the wood. When the tunnel is about one inch thick, the female will turn at a right angle and tunnel with the grain of the wood, drilling various chambers to create intricate tunnel systems. It is in these chambers that the carpenter bee female will lay her eggs. The female creates partitioned brood cells in which eggs are laid and provided with pollen and nectar. Adult carpenter bees emerge in late summer, but as winter nears, they find abandoned tunnels and hunker down to wait out the cold.
These gentle bees don’t mean to be pests, but their tendency to nest in eaves, siding, or decks is often at odds with human homeowners. There are many ways to control the carpenter bee population, and most popular solutions are lethal to the bee. The easiest way to prevent carpenter bees from nesting in your home is to paint untreated wood, or use plastic or vinyl siding. Leaving rotting tree stumps, old logs, bamboo, or pithy plants in your yard is an enticing alternative for these bees, and may even help your local bee population thrive.
Before getting out your pesticide or plugging their nest holes, consider the benefits of the carpenter bee. With the decline in bee populations around the world, local ecosystems need pollinators—and carpenter bees are some of the best. To ensure your garden thrives, keep carpenter bees around.
Credit: Thanks to My Backyard Birding for this video of large female carpenter bee. See the full video here.